1. Field of Invention
The present invention relates to a magnetic disk drive for reading and writing data on a magnetic disk, and relates in particular to a large-capacity magnetic disk drive that can handle improved, large-capacity magnetic disks having design features that surpass those of conventional magnetic disks.
2. Related Art
As data storage capacity has increased, or as software application programs have become larger, an increase in the capacities of magnetic disks has become obligatory, and as a result, the capacities of hard disks have been increased and various types of large-capacity storage devices have been developed.
Furthermore, by using recently developed techniques, conventional magnetic disk drives, i.e., so-called floppy disk drives, have been improved and can read and write both conventional low-density (2HD or 2DD) magnetic disks and magnetic disks having much larger capacities.
For example, a thin and compact read/write head is presently being employed that considerably narrows the pitches of tracks on a magnetic data recording medium, and in this manner, provides a considerable increase in the number of tracks. The use of such heads, when employed with chucking motors, motors that can change their speeds so that they correspond to those (e.g., 300 rpm or 360 rpm) appropriate for reading and writing low-density magnetic disks or to those (e.g., 3600 rpm or higher) appropriate for reading and writing high-density magnetic disks, can greatly increase the reading/writing speeds for magnetic data recording media. As a result, while maintaining compatibility with conventional flexible disks, provision is also made for the employment of magnetic disks having large capacities.
For this type of large-capacity magnetic disk drive, the technique for substantially extending the service life of the read/write head is discussed. According to this technique, the read/write head is shaped so that when a magnetic disk rotates rapidly, the head floats slightly above the surface of the magnetic disk, supported by pressure and an air stream that flows across the head. Therefore, when a speed (e.g., 3600 rpm) appropriate for reading and writing a high-density magnetic disk is selected, the read/write head can be prevented from directly contacting the magnetic recording medium and progressively abrading it.
As is described above, for a large-capacity magnetic disk drive, in order to reduce the abrasion caused by a read/write head, the head is supported by an air stream generated while revolving at high-speed so that it floats slightly above the surface of a magnetic disk. Also, a magnetic data recording medium that is used as a magnetic disk is considerably thinner than a magnetic data recording medium that is used as a hard disk. Therefore, when the disk revolution speed is changed to high, the data recording medium may be greatly deflected by negative pressure that is exerted near a shutter, so that under an abnormally high pressure condition it may come into contact with the read/write head, and due to this pressure, abnormal abrasion of the read/write head may occur.
Since, as a technical problem, the head-load pressure placed on the read/write head while it is revolving at high speed must be set in order to regulate this type of deflection, the objective of the present invention is the resolution of this problem.
To achieve the above objective, according to the present invention, a large-capacity magnetic disk drive comprises:
a head main body, for moving forward and backward along the tracks on a magnetic data recording medium;
a pair of vertically arranged read/write heads, which are flexibly supported at the head main body and which flexibly contact both magnetic data recording faces of the magnetic data recording medium;
a chucking motor, for changing the rotation speed of the magnetic data recording medium so that the number of revolutions is appropriate for either a high-density magnetic recording medium or for a low-density magnetic recording medium; and
head load pressure adjustment means, for adjusting, in consonance with the requirements for a high-density magnetic data recording medium or for a low-density magnetic data recording medium, a head load pressure for the pair of read/write heads exerted against the magnetic data recording faces of the magnetic data recording medium.
In addition, the head load pressure adjustment means includes:
a forcing member, for driving the top face of an upper carriage in a direction in which the head load is increased; and
a solenoid, for, when one end of the forcing member is driven a first distance in the direction in which the head load pressure is increased, setting the head load pressure to a pressure that is appropriate for reading and writing a low-density magnetic recording medium, and for, when the end of the forcing member is driven a second distance, which is smaller by a predetermined value than the first distance, in the direction in which the head load pressure is increased, setting the head load pressure to a pressure that is appropriate for reading and writing a high-density magnetic data recording medium.